Machines for processing sausages or frankfurters in an automatic and continuous manner using shirred casing sticks are well-known in the art. Particularly successful versions thereof from a commercial standpoint are the FRANK-A-MATIC machines, described in U.S. Pat. Nos. 3,115,668 and 3,191,222, incorporated herein by reference.
Adaptation of the FRANK-A-MATIC machine to accommodate co-extrusion of meat product, particularly meat emulsion and condiments such as cheese, mustard or ketchup, is described in VISCORA-FLASH publication #36 (1976) at pages 8 and 11. Co-extrusion is a relatively recent commercial development in meat processing technology whereby frankfurters can be made having a core of condiment, thereby eliminating the inconvenience and mess associated with the consumer's having to add condiment at the time of eating the frankfurter.
The condiment should be centered in the frankfurter core in order to minimize or avoid leaking of the condiment from the meat mass. Although not specifically discussed in connection with the FRANK-A-MATIC machine, a general system for centering an inner condiment tube inside the meat product outer tube to accommodate co-extrusion is described in the Viscora-Flash publication. The publication teaches the use of steel pins, as shown at page 9 thereof to achieve "perfect centering" of the inner tube inside the outer tube.
The above-described "perfect centering" system has disadvantages, however, inasmuch as meat fibers have the tendency to be caught by the steel pins, resulting in a clogging of the outer tube after accumulation of the meat fibers at the pins over a period of time.
French patent publication No. 2,450,063 discloses one possible solution to the above mentioned clogging problem by using bends in the inner tube, instead of steel pins, in order to effect "perfect centering" of the inner tube within the outer tube of a stuffing tube assembly. However, this solution would be expected to cause clogging problems at the point of contact between the inner and outer tube.
In view of the commercial importance of the above-discussed co-extrusion machines, new assemblies are needed.